Sequential in situ hydrotalcite precipitation and biological denitrification for the treatment of high-nitrate industrial effluent

Bioresour Technol. 2014 Nov:172:373-381. doi: 10.1016/j.biortech.2014.09.050. Epub 2014 Sep 19.

Abstract

A sequential process using hydrotalcite precipitation and biological denitrification was evaluated for the treatment of a magnesium nitrate (Mg(NO3)2)-rich effluent (17,000mgNO3(-)-N/L, 13,100mgMg/L) generated from an industrial nickel-mining process. The hydrotalcite precipitation removed 41% of the nitrate (7000mgNO3(-)-N/L) as an interlayer anion with an approximate formula of Mg5Al2(OH)14(NO3)2·6H2O. The resultant solute chemistry was a Na-NO3-Cl type with low trace element concentrations. The partially treated effluent was continuously fed (hydraulic retention time of 24h) into a biological fluidised bed reactor (FBR) with sodium acetate as a carbon source for 33days (1:1 v/v dilution). The FBR enabled >70% nitrate removal and a maximal NOx (nitrate+nitrite) removal rate of 97mg NOx-N/Lh under alkaline conditions (pH 9.3). Overall, this sequential process reduced the nitrate concentration of the industrial effluent by >90% and thus represents an efficient method to treat Mg(NO3)2-rich effluents on an industrial scale.

Keywords: Bioreactor; Denitrification; Effluent; Fluidised bed reactor; Hydrotalcite.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aluminum Hydroxide / chemistry*
  • Denitrification / physiology
  • Fractional Precipitation / methods*
  • Industrial Waste / prevention & control*
  • Magnesium Hydroxide / chemistry*
  • Mining
  • Nitrates / chemistry
  • Nitrates / isolation & purification*
  • Nitrates / metabolism*
  • Oxidation-Reduction
  • Sewage / chemistry*
  • Sewage / microbiology*
  • Systems Integration

Substances

  • Industrial Waste
  • Nitrates
  • Sewage
  • hydrotalcite
  • Aluminum Hydroxide
  • Magnesium Hydroxide